Gearshift forks are used in manual transmissions of automotive vehicles which are configured with a countershaft structure. Through these gearshift forks, the selector rods cooperate with sliding sleeves that couple idler pinions through coupling elements to the main shaft or to the countershaft. The invention therefore concerns a gearshift fork for a manual transmission of an automotive vehicle, which gearshift fork is connected to a selector rod and engages with its bifurcated section into a peripheral groove of a sliding sleeve, said bifurcated section extending transversely of the central longitudinal axis of the selector rod.
A gearshift fork of the pre-cited type is described in the textbook xe2x80x9cJohannes Loomann Zahnradgetriebe, 1970 Edition, pages 96 to 98 and page 102xe2x80x9d. A distinction must be made between gearshift forks that are arranged rigidly on the selector rod and gearshift forks that are guided for pivoting in a so-called gearshift rocker. In both cases, the gearshift fork has a bifurcated projection that engages into a peripheral groove of the sliding sleeve, and a collar which serves to stiffen the entire gearshift fork and through which the gearshift fork is fixed on the selector rod or in the gearshift rocker. According to the state of the art, gearshift forks are made as die-cast parts out of aluminium. This method of fabrication is relatively uneconomical for large-series production which is required in the field of transmissions of automotive vehicles.
The object of the present invention is therefore to provide a gearshift fork that is suitable for manufacturing in large series and can be produced reliably using simple means.
The invention achieves this object by the fact that the gearshift fork comprising a stiffening in the form of an angled collar is made as a complete component by shaping without chip removal. In this way, it is possible to produce a gearshift fork which possesses a high degree of stiffness and is not subject to the risk of fracture despite its small overall dimensions and high bending loads. Due to the chipless shaping method, the gearshift fork can be manufactured very economically.
A further feature of the invention concerns a method of manufacturing the aforesaid gearshift fork, according to which method, the gearshift fork is made by deep drawing. Deep drawing is an extremely simple and reliable method and suitable for manufacturing components subjected to high loading. According to the invention, two gearshift forks are manufactured by deep drawing in one work step and are initially in the form of a pot-shaped component. The two gearshift forks are formed in the pot-shaped component as mirror images of each other. The bifurcated sections of the two gearshift forks which are connected to each other have then only to be separated from each other.
A particularly suitable embodiment of a gearshift fork to be manufactured as a deep drawn part is a gearshift fork whose collar extends at a right angle to the bifurcated section on one side. The gearshift fork can be fixed on the selector rod by welding.